Question 323 GTX fuel pump not turning on.

[G.T.R]

Well I just got my 323 re assembled, but I am encountering an issue where it will crank and crank, would not start, but I observed that the fuel pump was not priming, the fuel pump was the one out of that car and apparently works fine. I am going to dig into it more tomorrow and test the connectors etc.

I checked around and could not find a fuse for a fuel pump, but all the fuses are good, but it just doesnt seem right that its not fused? Am I missing something here? Any guidance would be great this is my first mazda, and I am used to fixing my skyline GTR and land rover.

Thanks in advance
Steve

[jay]

There's a relay in the pax footwell, mounted on the same bracket as the ECU. Check to make sure that thing is working.

[1st Gen]

So your using the same set up that worked before in this car? If I misunderstand, please clarify. What kind of set up are you using?
I used a JDM engine/ecu/harness/vaf in a USDM BG and had to do the fuel pump/vaf wiring fix.

[jay]

In my GTX we had problems with that relay getting hot. Pretty much all stock GTX stuff cept for a 93 rx7 pump, and bigger wires going to it. Those partially solved the pump relay blowout problem, but it just seems that thing runs pretty hot. There is also IIRC, a pump fuse under the hood near the battery, but it's been a few years so I might be wrong...

[G.T.R]

okay, this is an oem fuel pump, and no power was getting to the pump, so I hard wired it to the battery with a kill switch, thicker wires and a ground, it roared to life, but then died shortly after now all it will do is crank. I am getting fuel to the rail though, spark is amazing, and the car makes good compression, would this bad relay cause the injectors not to fire? Ill give a hunt for those fuses now.

Also to clarify this is a stock 323 GTX, USDM stock fuel pump, just bigger wires.

update, swapped the relays near the ecu with known working ones no change, swapped the ecu with a known working one no change. I checked the small fuse box to the battery but the only thing in there is a fuse for the fuel injection but its not blown. I really dont know what else to check here, the wiring is good everything else works on the car, is just not pumping fuel and no firing.

[G.T.R]

okay, my injectors will not fire, any ideas? I get fuel to the rail, but upon crank nothing comes out?

[jay]

All you can do now is get your meter out, start at the injectors, and work your way back till you find juice.

[G.T.R]

All you can do now is get your meter out, start at the injectors, and work your way back till you find juice.

thanks for the help jay guidance is great, when I get some time off ill tackle it again, anyone have a diagram for this car so i can see what it goes into from there on and is there anything else on the car that when faulty would cause this to happen ? CAS , position sensor?

regards
steve

[SgtRauksauff]

I thought the GTXes had two pumps. one transfer pump to get from one side to the other side, over the hump the driveshaft goes through. Then the other was the main pump. Under the drivers seat was a small computer that controlled the fuel pumps, including a delay circuit so the transfer pump wouldn't keep running all the time.

Maybe a loose connection or something funky down there???

--sarge

[BFMRGTX]

Check the AFM connector too, that will give the same symptom. There is a yellow, 2-pin connector on the firewall, behind the intake plenum, that is used to test the fuel pump pressure. Remove the hose from the filter outlet, put a hose on the outlet to a bucket/bottle. Put a jumper on the two pins and turn on power. The gas should be flowing fast in to the bucket/bottle.

If it's a no-go, then start working back from the filter to the pump.

If it's a go, then start looking at the regulator, fuel rail, injectors, return line, etc. Then start troubleshooting the electrical system.

[G.T.R]

Okay .

i checked and I am getting juice at the connectors, now my question is there a relay that trips the fuel pump, because right now the fuel pump is hard wired, but my guess is because it is, the car isnt sensing that optimal fuel pressure it reached, it keeps running the fuel pump and I am over fueling or the pressure regulator is not opening.

So where can I find the relay that controls the fuel pump, I already checked the ones behind the ECU but there must be more.

steve

[G.T.R]

going to go work on it shortly, gonna try and pull and test all my relays, anyone have any idea's or relays that might not cause the injectors to fire? my guess it there has to be a bad relay causing a signal not to transmit because the injectors are not firing

[trailrider098]

Okay .

i checked and I am getting juice at the connectors, now my question is there a relay that trips the fuel pump, because right now the fuel pump is hard wired, but my guess is because it is, the car isnt sensing that optimal fuel pressure it reached, it keeps running the fuel pump and I am over fueling or the pressure regulator is not opening.

So where can I find the relay that controls the fuel pump, I already checked the ones behind the ECU but there must be more.

steve

The GTX has a return system, so pressure is controled by the small reg at the end of the fuel rail. Pressure is slightly adgusted by the vacume line going to the regulator. There is also no sensors in the fuel system that control or regulate the pressure, its all done by that one mechanical regulator on the rail

Also, on a stock GTX when you turn the key to the ON position the fuel pump should prime quick and then shut off. Once the car is started and the flapper door on the AFM opens the fuel pump will come on again

[G.T.R]

Okay I checked the injectors and I am not getting a ground pulsation upon cranking, my friends 323 does but mine does not, I tried swapping over my ecu to his and his car fired right up, I am on the hunt for something that is un plugged or broken hmmmm.

Also this seems to be related to my issue of not getting power to my fuel pump at least not a good amount of it only 4V not enough to toggle the pump.

I tried checking through the items mentioned by swapping over with working items and they all worked when installed on his car. I am seriously racking my brain here because its a 1988 Mazda, if I can find problems and fix them on my land rover this cant be that difficult and illuding, but I also noted that I have a check engine light on the dash, the work shop manual shows using a checker to check the code, so is there a way to view it manually?

[G.T.R]

GREAT NEWS EVERYONE SHE FIRES AND RUNS NOW!!!.

Dont ask me how, dont ask me why, but was wrenching for a good 4 hours, thought we had it nailed as a bad fuel pressure regulator swapped it and nothing, getting ready to give up for the day when my friends dad walks in, un plugs the maf, and she fires up, waited a bit plugged the maf back in now she runs and starts perfectly every time...... I am at a loss for words but happy she is running, found out I have a big oil leak some where, and its pissing coolant aswell, once those things are done she is good to go, cant wait